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geekhack Community => Keyboards => Topic started by: Kamen Rider Blade on Mon, 10 February 2014, 01:20:27
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Just curious as to whether any keyboard case / housing is made out of PBT instead of ABS?
BTW, I'm not talking about Keycaps.
If anybody knows this answer and can point at an example, that would be great.
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Matias makes theirs out of polycarbonate.
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Matias makes theirs out of polycarbonate.
IIRC polycarbonate and PBT are different substances.
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IIRC polycarbonate and PBT are different substances.
Obviously. https://en.wikipedia.org/wiki/Polybutylene_terephthalate https://en.wikipedia.org/wiki/Polycarbonate
The OP may still be interested, though, as polycarbonate has many material advantages over ABS.
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I don't think it would be a wise idea to mold a case out of PBT as PBT is naturally brittle -- it would cause unneeded troubles during shipping for the retailer+manufacturer.
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Zeal got it. You want a plastic that is impact-resistant, I.e. bends instead of cracks if it is bent. PC is good at that. ABS exists in several types, of which some are more than others. There is also PC-ABS blend and PVC.
PVC is being phased out because manufacturing byproducts being harmful for the environment.
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Zeal got it. You want a plastic that is impact-resistant, I.e. bends instead of cracks if it is bent.
We call such a material property "toughness". It's the area under the stress/strain curve and represents how much energy a material can absorb before failure. Diamonds have high (very high) young's modulus, but very low toughness: you can crack them with a hammer (they also burn. I've never been a fan). PBT is the same way (you can look up the destructive hammer test for PBT)
As far as other materials, assuming cost is no object, PC/ABS blends were very popular for computer cases a few years ago, now it seems everyone has moved to magnesium (which has similar issues to PBT: It's not ductile enough for my taste) or a fiber reinforced PC/ABS blend. The reinforcing fibers sacrifice some durability in favor of much higher strength: it's really up to the use case if this is a good idea or not.
I'd like to see a FR-PC+ABS keyboard case, but I'm not sure it'll be cheap enough.
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Zeal got it. You want a plastic that is impact-resistant, I.e. bends instead of cracks if it is bent.
We call such a material property "toughness". It's the area under the stress/strain curve and represents how much energy a material can absorb before failure. Diamonds have high (very high) young's modulus, but very low toughness: you can crack them with a hammer (they also burn. I've never been a fan). PBT is the same way (you can look up the destructive hammer test for PBT)
As far as other materials, assuming cost is no object, PC/ABS blends were very popular for computer cases a few years ago, now it seems everyone has moved to magnesium (which has similar issues to PBT: It's not ductile enough for my taste) or a fiber reinforced PC/ABS blend. The reinforcing fibers sacrifice some durability in favor of much higher strength: it's really up to the use case if this is a good idea or not.
I'd like to see a FR-PC+ABS keyboard case, but I'm not sure it'll be cheap enough.
What do you mean when you state "FR-PC", what material is that?
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Filler/Fiber reinforced polycarbonate and ABS blend I'm guessing?
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iirc, the majestouch 2 newer revisions have been made with pbt casing.
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iirc, the majestouch 2 newer revisions have been made with pbt casing.
I remember reading this as well. The case of my MJ2 has a rough texture while my Filco keypad has a smooth texture.
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Now I understand why manufacturers use ABS for keyboard case's / housing's.
That bending nature of it is very nice compared to shattering under high pressure.
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http://www.youtube.com/watch?v=JyaYVLjlGhg (http://www.youtube.com/watch?v=JyaYVLjlGhg)
Now I understand why manufacturers use ABS for keyboard case's / housing's.
That bending nature of it is very nice compared to shattering under high pressure.
That is why when you drop a Model-M onto a concrete floor it will shatter/crack the casing, but a Filco just bounces with no damage, trust me I've experimented this when I was loaded back in 2012 :thumb: .
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Is there a way to coat ABS plastic to prevent it from yellowing when hit with UV light?
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Filler/Fiber reinforced polycarbonate and ABS blend I'm guessing?
Yes, this is how they are stamped usually. I suspect it has something to do with RoHS.
Is there a way to coat ABS plastic to prevent it from yellowing when hit with UV light?
Yes, but as far as I know, modern plastics don't have the same additives that were used back in the day that turned yellow. I think it has something to do with bromine or whatever was added as a fire retardant then that causes yellowing primarily.
iirc, the majestouch 2 newer revisions have been made with pbt casing.
Very interesting. I never knew this. I can only wonder why they would do that.
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iirc, the majestouch 2 newer revisions have been made with pbt casing.
Which ones?